1. Field of the Invention
The present invention relates to an ion-implantation system for fabricating a semiconductor device and, more particularly, to an ion-implantation system for fabricating a semiconductor device, whose respective components are rearranged in a manner so as to save space, by being installed partially in and partially adjacent to a semiconductor manufacturing line.
2. Background of the Related Art
In general, an ion-implantation system in a semiconductor device manufacturing line is capable of regulating the concentration of an impurity in the range of 10E14.about.10E18 atoms/cm.sup.3, which is superior to prior methods such as diffusion for regulating that concentration. The ion-implantation system is widely used due to its ability to inject the impurity to a precise depth, particularly as the level of integration of semiconductor devices increases.
In general, the above described ion-implantation system comprises an ion source, an ion extractor, an ion exchanger, an ion mass analyzer, an ion accelerator, an ion converging means and an end station including the assembly of a Faraday cup and a disk on which a wafer is placed.
A high voltage of various levels is applied to the respective components for the purpose of ion-decomposition, extraction and acceleration. The high voltage changes the gas generated from the ion source into plasma and the electric field formed from this applied voltage induces the extraction of positive ions. Then, only desired ions out of the extracted ions are refracted and accelerated so as to be injected into the wafer to an appropriate depth.
FIG. 1 is a schematic view of a conventional ion-implantation system, including: a semiconductor wafer 10; the impurity source (not shown) containing the impurity to be injected by providing the impurity in gas or solid form to an ion source 12; and the ion source 12 having a power source and a vacuum pump therein generating a plasma of the supplied impurity and ionizing the plasma.
Positive ions are generated from the ion source 12 through an ion outlet 13 by applying an appropriate voltage to the ion source 12. The extracted positive ions are changed into negative ions in an ion exchanger 14 using magnesium.
The changed negative impurity ions go into an accelerator 18 via an ion mass analyzer 16, which is based on the different diameters of refraction with respect to different weights of the ions in the electric field. Because the accelerator 18 has a voltage source therein, the negative impurity ions obtain high energy before entering a charge exchange and acceleration chamber 20. The ion beam 26, which passed a charge filter 21, undergoes ion-converging, projecting and charge-classification processes, and the ion beam is then injected into a designated site on the wafer 10 placed on the disk 22. To measure a dose of the impurity, the disk 22 has a Faraday cup assembly 24, to which a backward voltage is applied so as to prevent the generation of secondary electrons due to ion-implantation, and a measuring instrument 28 to measure the dose of the impurity based on the current of the ion beam.
In the conventional ion-implantation system of FIG. 1, the ion mass analyzer 16 is located such that the ion beam is horizontally refracted, and the components from the ion source 12 through to the disk 22 having the wafer 10 thereon are all arranged in the same area of the semiconductor device manufacturing line and along the same horizontal plane.
The conventional ion-implantation system therefore takes up too much space in the semiconductor device manufacturing line, in which space-saving has become a priority for cost-reduction and product-performance reasons.